Concrete structures require a system of joints to provide for expansion and contraction of the concrete caused by fluctuations of the surrounding temperature. Such expansion joints often comprise (1) a bridge device which connects two sections of concrete and (2) an end dam nosing material which fills the channels (also called end dams) between the bridge device and each concrete section. The bridge device must be flexible to adjust to the expansion and contraction of the gap between the concrete sections. The nosing material must ensure a watertight seal between the bridge device and the concrete sections and, in addition, maintain the joint flush with the surface of the concrete.
With concrete parking decks, bridges and road structures, the expansion joints are exposed to weather and repeated impacts from vehicles. These factors can cause the concrete sections and the expansion joints to flex between the supporting members of the concrete sections. Expansion joints are also exposed to corrosive substances such as oil, gasoline, diesel fuel, transmission fluid and the like from those vehicles.
Therefore, the end dam nosing material (also referred to simply as the nosing material) must bond to the concrete and to the bridge device. At the same time, the nosing material must possess a high level of tensile and compressive strengths and flexural capabilities to withstand the expansion and contraction of the concrete and the repeated impacts from the vehicles. Also, the nosing material must possess a high level of chemical resistance to withstand exposure to water, ice, and the corrosive substances from the vehicles.
Concrete and various synthetic resins have previously been used as end dam nosing materials. Concrete has several drawbacks, including brittleness and a tendency to crack and disintegrate under stress. In addition, concrete is not easily produced in batches small enough to be used as an end dam nosing material. Synthetic resins (such as epoxies) possess good bonding capabilities but tend to become brittle and lose flexural capabilities at lower temperatures. Because of the lack of flexural capabilities of concrete and synthetic resins, end dam nosing materials made of those substances tend to crack, debond from the concrete and pop out of the end dams when the expansion joint is subjected to flexural loads.
More flexible synthetic resin mixtures, such as those incorporating polyureides, tend to decompose when exposed to water and chemicals emitted from vehicles. In addition, prior art synthetic resin mixtures require external heat to cure (vulcanizing process). This often involves preheating the components of the nosing material, heating the components as they are combined in a mixer, applying the nosing material to the expansion joint with heated tools and heating the expansion joint until the nosing material cures. The equipment and manpower required to perform all of the heating steps involved in this curing process make the installation of such nosing materials time consuming, awkward and costly.
Therefore, there is a need for an end dam nosing material which is useful for expansion joints and which possesses high levels of bonding strength, tensile strength, compressive strength, flexural capabilities and resistance to chemical action. There is also a need for an end dam nosing material which does not require the application of external heat for curing.